The taconian age of tectogenesis as the start of island-arc events in the development of the Ural fold region

About the authors:

Viktor D. Starkov, Cand. Geolog.-Mineral. Sci., Professor, Department of Physical Geography and Ecology, Tyumen State University
Andrey S. Aleksandrov, student, Institute of Earth Sciences, Tyumen State University

Abstract:

The Taconian age of the tectogenesis saw the emergence of island-arc events in the development of the Ural fold region. This event marked the beginning of the formation of structural and formational zones which were further developed in the Silurian-Triassic period.The emergence of island-arc events is associated with the emergence of the ultradeep fault zone (the subduction zone) within the oceanic plate whose purpose was to relieve the compressive stress accumulated at the periphery of the oceanic structure. The surface fault zone fell to the east, toward the open ocean. Above the subduction zone, the emerging underwater volcanic uplift gradually grew into the archipelagos of surface islands. Water ultrametamorphism developed on the ophiolites of the melanocratic base in the hanging wall of the subduction zone. The beginning of the island-arc stage throughout the western periphery of the Ural paleoocean coincides with one fixed period of time at the end of the Ordovician, that of the early Silurian Period. The end of the stage in different areas of the Ural paleooceanic zones stretches in time from later Silurian to Early Carboniferous Period. Yet, the emergence of typical island-arc associations did not start immediately. Ample evidence shows that the intrusive and volcanic complexes of the internal zones of the Urals were formed on the metamorphosed and partially granitized ophiolites of the Pre-Silur Age.

References:

1. Stille, H. Grundfragen der vergleichenden Tectonic. Berlin: Verlag von Gebruder Borntraeger, 1924. Ruckblik.

2. Pronin, A.A. Osnovnye cherty istorii tektonicheskogo razvitiia Urala. Kaledonskii tsikl [Basic Features of History of the Urals Tectonic Development. Caledonian Cycle]. Leningrad: Nauka, 1971. 215 p. (in Russian).

3. Sorokhtin, O.G. Teoriia tektoniki litosfernykh plit — sovremennaia geologicheska-ia teoriia [Theoretical Foundations of Tectonics of Lithosphere Plates — the Modern Geological Theory]. Moscow, 1984. 40 p. (in Russian).

4. Karetin, Iu.S. Geological aspects of metamorphism in the zone of platiniferous belt, in Geologiia metamorficheskikh kompleksov Urala [Geology of Metamorphic Complexes of the Urals]. Sverdlovsk, 1976. Pp. 66-72. (in Russian).

5. Nestoianova, O.A. Basic stages of development of the Middle Paleozoic volcanism of Magnitogorsk synclinorium / In: Materiali po geologii i poleznim iskopaemim Urala [Materials on Geology and Natural Resources of the Urals]. 1961. Vol. 8. Pp. 20-25.(in Russian).

6. Fershtater, G.B., Malakhova, L.V., Borodina, N.S. i dr. Evgeosinklinal’nye gabbro-granitnye serii [Eugeosynclinal gabbro-granite series]. Moscow: Nauka, 1984. 264 p.(in Russian).

7. Starkov, V.D. Intruzivnyi magmatizm evgeosinklinal’nykh zon Poliarnogo Urala [Intrusive magmatism of eugeosynclinal zones of the Arctic Urals]. Sverdlovsk, 1985. 148 p. (in Russian).

8. Starkov V.D., Kholodnov V.V. Features of eugeosynclinal granitoid magmatism In the Arctic Urals, in: Petrologiia i rudoobrazovanie [Petrology and Mineralization]. Sverdlovsk: UNTs AN SSSR, 1986, Pp. 37-43 (in Russian).

9. Kamaletdinov, M.A., Kazantseva, T.T., Kazantsev, Iu.V. The scheme of Paleozoic volcanism in the Urals, in Dokembriisko-paleozoiskaia istoriia razvitiia Urala [Precambrian and Paleozoic History of the Urals]. Sverdlovsk, 1980. Pp. 46-47. (in Russian).

10. Efimov, A.A., Chashchukhin, I.S. The main ophiolite belt of the Urals: the area of abnormal mantle evolution of gabbro-ultramafic complexes, in Ofiolity: geologiia, petrologiia, metallogeniia i geodinamika [Ophiolites: Geology, Petrology, Metallogeny and Geodynamics]. Ekaterinburg, 2006. Pp. 12-17. (in Russian).

11. Efimov, A.A., Iakovleva, O.M. Real and facial similarity between metavolcanic complexes: to the problem of correlation of tectonic and magmatic events in the main gabbro-ultramafic belt of the Urals, in Geodinamika, magmatizm, metamorfizm i rudoo-brazovanie [Geodynamics, Magmatism, Metamorphism and Mineralization]. Ekaterinburg, 2007. Pp. 135-144. (in Russian).

12. Ivanov, S.N., Korinevskii, V.G., Belianina, G.P. Relikty riftovoi okeanicheskoi doliny na Urale [Relics of Oceanic Rift Valley in the Urals]: Proceedings of the USSR Academy of Sciences. 1973. Vol. 211. № 4. (in Russian).